In a process of implementing the technical solutions of the embodiments of the disclosure, the inventor of the disclosure at least finds that the related art has the technical problems as follows.
D2D communication refers to direct communication between neighbouring devices, such as Bluetooth. Due to lack of network management and control, the D2D communication generally adopts unlicensed spectra such as 2.4 GHz. As smart phones are rapidly popularised, many new applications, such as location-based applications and social networking applications, has emerged. In a mobile communication network, as shown in FIG. 1, due to the fact that a network operator needs to manage and control a licensed spectrum, communications between UEs must be performed via a network even if two devices are located at neighbouring positions. When two communication parties communicate using the licensed spectrum, the network must be adopted so as to achieve the network-based resource scheduling, charging and management for communication activities. In order to reduce load on the network, some companies propose conceptions of direct communication between neighbouring devices. As shown in FIG. 2, a solid line represents a communication path of a user plane, and a dotted line represents a communication path of a control plane. At present, the 3rd Generation Partnership Project (3GPP) begins to research the D2D communication. At present, D2D includes two aspects: discovery and communication. The discovery refers to identification of a UE running a D2D application and having a D2D capability in a neighbouring area, and the communication refers to that a D2D UE performs user plane data transmission via inter-user direct connection or via an evolved Node B (eNB).
A public security network provides communication for public service such as public security, fire service and first aid. A public security system needs high robustness and a specific communication requirement for solving emergency service communication. A representative system is a Terrestrial Trunked Radio (TETRA) system defined by the European Telecommunications Standards Institute (ETSI), which can provide a series of functions which were not supported by a commercial cellular system before. Emergency communication also belongs to public security communication.
An application scenario of the D2D technology includes a network coverage scenario (for instance, commercial applications) and a network coverage-free scenario (for instance, public security communication).
Generally, in the network coverage scenario, a network side manages a D2D UE to implement control plane process; in the network coverage-free scenario, a D2D UE implements a control plane process by itself. The D2D technology can be applied to a point-to-point or point-to-multipoint environment such as D2D unicast or broadcast communication.
However, there is not a solution for D2D broadcast communication in a network coverage-free scenario, namely outside a network coverage area, in the related art.